(a) Field of the Invention
This invention relates to a circuit breaker housing which is made of insulating material which is divided into upper and lower parts along a parting gap, and which has stepwise overlapping partitions between pole channels.
(b) Description of the Prior Art
A circuit breaker of this type, but in which the stepwise overlap of the partitions is found only sectionally, is described in U.S. Pat. No. 3,632,939 (corresponding to British Pat. No. 1,300,203). If such circuit breakers are subjected to heavy electrical stresses, the switching gases produced in the arcing chambers can get into the adjacent pole channel and around the overlapping sections provided in the vicinity of the arching chambers at the partitions. Internal breakdowns can thus come about in spite of the protective measures provided.
A further difficulty arises if identical breakers are to be mounted directly side by side in a switching installation or on a switchboard. Then, the switching gases escaping at the parting gap between the upper part and the lower part of one breaker can get into the adjacent pole channel of a neighboring circuit breaker. Again, breakdowns can occur. In both exposed regions, at the partitions and at the outer walls of adjacent breakers, electrical leakage paths can form in the course of time which are detrimental to reliable operation of the breaker.